Manipulator

ABSTRACT

A manipulator comprises an operation command unit provided with an attitude adjusting unit and an end effector control unit, a connecting unit having one end connected to the operation command unit, a working unit connected to the other end of the connecting unit and provided with an end effector and a support unit supporting the end effector for motions, and a control unit that transmits an operation command provided by the attitude adjusting unit to the support unit to adjust the attitude of the end effector and transmits an operation command provided by the end effector control unit to the end effector to operate the end effector. The support unit includes a first joint capable of turning about a first axis perpendicular to the center axis of the connecting unit, and a second joint capable of turning about a second axis perpendicular to the first axis. The end effector can be turned for rolling about an axis substantially parallel to the second axis of the second joint. The attitude adjusting unit has a third joint having a third axis perpendicular to the center line of the connecting unit. The end effector control unit is formed such that the fingers of an operator gripping operating members included in the end effector control unit extend substantially in parallel to the fourth axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manipulator and, more particularly,to a medical manipulator of a simple mechanism excellent in operability.

2. Description of the Related Art

Referring to FIG. 25, when practicing laparoscopic-surgical operation,such as cholecystectomy, some small holes 151, 152 and 153 are formed inthe abdomen of a patient 150 and tubes 154 are inserted in the holes151, 152 and 153. An endoscope 161 and forcepts 171 and 172 are insertedthrough the tubes 154 in the abdomen. An operator 160, i.e., a surgeon,performs a surgical operation observing images taken by the endoscope161 and displayed by a monitor 162. Such an operative method does notneed laparotomy and reduces physical burden on the patient and reducesgreatly the number of days necessary for the patient to recover and toleave the hospital after the operation. However, it is a problem in somecases that the operator 160 is unable to observe a diseased partdirectly. Furthermore, the forcepts 171 and 172 are provided with onlygrippers capable of opening and closing, it is difficult to change theattitude of the grippers freely and hence the forcepts 171 and 172 arepoorly operable. Accordingly, only skilled operators are able to performthe foregoing operative method properly. It takes a very long time foroperators to attain proficiency in the operative method using theendoscope.

Studies have been made to solve such problems by applyingremote-controlled robots, such as master/slave manipulators, to themedical field. The remote controlled robot is a robot system including amaster arm to be operated by an operator, and a slave arm to act on adiseased part. The master arm and the slave arm are completelyseparated. Electric signals representing commands provided by operatingthe master arm are given to the slave arm. Usually the master arm andthe slave arm are articulated arms having at least six degrees offreedom of motion. The master/slave manipulator is provided withcontrollers for controlling slave arms for operations in six degrees offreedom of motion and is a complicated system including many electriccontrol systems, many parts and many wiring lines. Because of itscomplexity, the reliability of operations of the master/slavemanipulator is not on a satisfactorily high level. The master/slavemanipulator is a large-scale system, expensive and needs a highmaintenance cost. The operator operates the master/slave manipulator ata position remote from the patient and hence the operator is unable togive medical treatment quickly to the patient in an emergency.

The inventors of the present invention proposed a medical manipulatorshown in FIG. 26 in Jpn. Pat. App. No. Hei 11-165961. As shown in FIG.26, this previously proposed medical manipulator includes an operationcommand unit 20 including a attitude adjusting unit 23 and an endeffector control unit 24, a connecting unit 30 having one end connectedto the operation command unit 20, a working unit 10 connected to theother end of the connecting unit 30 and provided with an end effector 14and support units 15 and 16 supporting the end effector 14 foroperations in at least two degrees of freedom of motion, and acontroller, not shown, capable of transmitting an operation commandprovided by the attitude adjusting unit 23 to the support units 15 and16 to adjust the attitude of the end effector 14 and of transmitting anoperation command provided by the end effector control unit 24 to theend effector 14 to operate the end effector 14. In the working unit 10and the operation command unit 20, the support units 15 and 16 have apitching shaft and a yawing shaft, respectively, and the end effector 14is a gripper.

Referring to FIG. 27, when the medical manipulator is used for suture,the end effector 14 grips a curved suture needle 180 threaded with athread 181, sticks the suture needle 180 into a part to be sutured andmoves the curved suture needle 180 along a circular path. Since requiredoperations and the degree of freedom of motion are not properlycoordinated in the known medical manipulator shown in FIG. 26, theoperation command unit 20 is unable to operate smoothly for operationsin directions intended by the operator. Thus, the operability of theknown medical manipulator is unsatisfactory. When the working unit 10and the operation command unit 20 are in some positions, respectively,the degree of freedom of motion of the end effector 14 is reduced, theend effector 14 is set in a singular attitude and the operability of theend effector 14 in particular directions becomes unsatisfactory.Moreover the gripping force of the end effector 14 is insufficient.

SUMMARY OF THE INVENTION

The present invention has been made in view of the aforesaid problems inthe conventional medical manipulators and it is therefore an object ofthe present invention to provide a manipulator having simpleconstruction and high reliability and excellent in operability.

According to one aspect of the present invention, a manipulator includesan operation command unit provided with a attitude adjusting unit and anend effector control unit, a connecting unit having one end connected tothe operation command unit, a working unit connected to the other end ofthe connecting unit and provided with an end effector and a support unitsupporting the end effector for motions in at least two degrees offreedom of motion, and a control unit that transmits an operationcommand provided by the attitude adjusting unit to the support unit toadjust the attitude of the end effect or and transmits an operationcommand provided by the end effector control unit to the end effector tooperate the end effector; wherein the support unit includes a firstjoint capable of turning about a first axis perpendicular to the centeraxis of the connecting unit, and a second joint capable of turning abouta second axis perpendicular to the first axis, the end effector has acenter axis substantially parallel to the second axis, the attitudeadjusting unit includes a third joint capable of turning about a thirdaxis perpendicular to the center axis of the connecting unit and afourth joint capable of turning about a fourth axis perpendicular to thethird axis, the end effector control unit is provided to be gripped byfingers extending substantially in parallel to the fourth axis.

In the manipulator according to the present invention, the end effectorhas two working joints mounted on the second joint, the two workingjoints being capable of turning about the second axis, the two workingjoints are rotated in the same direction to rotate the second joint, andthe two working joints are rotated in opposite directions, respectively,to drive the end effector for gripping and releasing actions.

In the manipulator according to the present invention, two working linksare supported on the two working joints, respectively, and capable ofturning about axes in directions parallel to and in directionsperpendicular to the axis of the two working joints, and the workinglinks are rotatably joined together.

The manipulator according to the present invention may further include asensor capable of measuring force acting in a direction perpendicular tothe axes of the third and fourth is joint and included in the operationcommand unit; and an actuator combined with the connecting unit andcapable of applying a torque to the connecting unit to urge theconnecting unit to turn about its axis; wherein the actuator iscontrolled on the basis of a value measured by the sensor.

In the manipulator according to the present invention, the sign of thetorque produced by the actuator may be controlled on the basis of therelation between the sign of an angle indicating the angular position ofthe third joint and that of the value measured by the sensor.

In the manipulator according to the present invention, the torqueproduced by the actuator may be controlled to vary in proportion to thevalue measured by the sensor.

In the manipulator according to the present invention, a working unitprovided with an end effector and a support unit supporting the endeffector for motions in at least two degrees of freedom of motion;wherein the support unit includes a first joint capable of turning abouta first axis, and a second joint capable of turning about a second axisperpendicular to the first axis, wherein the working unit has twoworking joints mounted on the second joint, the two working joints beingcapable of turning about the second axis, the two working joints arerotated in the same direction to rotate the second joint, and the twoworking joints are rotated in opposite directions, respectively, todrive the end effector for gripping and releasing actions.

In the manipulator according to the present invention, two working linksare supported on the two working joints, respectively, and capable ofturning about axes in directions parallel to and in directionsperpendicular to the axes of the two working joints, and the workinglinks are rotatably joined together.

According to the present invention, the support unit is capable ofsupporting the end effector for motions in at least two degrees offreedom of motion, and the operation command unit and the working unitare connected mechanically by the connecting unit. Therefore,satisfactory operability and high reliability, which are the features ofthe manipulator previously proposed in Jpn. Pat. App. No. Hei 11-165961,are not spoiled. Since the actual actions of the operator, such asoperator's actions for moving a curved suture needle for suturing, andthe motions of the manipulator are identical, the operation command unitcan be smoothly moved in a direction desired by the operator. Thus, themanipulator is excellent in operability. Since operating force exertedby the operator is assisted by power when the end effector is set in asingular attitude or an attitude similar to the particular attitude, theoperability of the end effector in particular directions does notbecomes quite unsatisfactory and the end effector is able to exert asufficiently high gripping force.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following description takenin connection with the accompanying drawings, in which:

FIG. 1 is a schematic perspective view of a medical manipulator in afirst embodiment according to the present invention;

FIG. 2 is a skeleton drawing of the medical manipulator shown in FIG. 1;

FIG. 3 is a skeleton drawing of assistance in explaining the operationof the medical manipulator shown in FIG. 1;

FIG. 4 is a schematic perspective view of a working unit included in themedical manipulator shown in FIG. 1;

FIG. 5 is a schematic perspective view of a working unit included in themedical manipulator shown in FIG. 1;

FIG. 6 is a schematic perspective view of a working unit included in themedical manipulator shown in FIG. 1;

FIG. 7 is a schematic perspective view of an end effector control unitthat may be employed in the medical manipulator shown in FIG. 1;

FIG. 8 is a schematic perspective view of an end effector control unitthat may be employed in the medical manipulator shown in FIG. 1;

FIG. 9 is a schematic perspective view of an end effector control unitthat may be employed in the medical manipulator shown in FIG. 1;

FIG. 10 is a schematic perspective view of an end effector control unitthat may be employed in the medical manipulator shown in FIG. 1;

FIGS. 11(a) and 11(b) are a front elevation and a side elevation,respectively, of a working unit that may be employed in the medicalmanipulator shown in FIG. 1, in which gripping bars are at releasingpositions, respectively;

FIGS. 12(a) and 12(b) are a front elevation and a side elevation,respectively, of the working unit shown in FIG. 11 in a gripping state;

FIGS. 13(a) and 13(b) are a front elevation and a side elevation,respectively, of a working unit that may be employed in the medicalmanipulator shown in FIG. 1 in a releasing state;

FIGS. 14(a) and 14(b) are a front elevation and a side elevation,respectively, of the working unit shown in FIG. 13 in a gripping state;

FIGS. 15(a) and 15(b) are a front elevation and a side elevation,respectively, of a working unit that may be employed in the medicalmanipulator shown in FIG. 1 in a releasing state;

FIGS. 16(a) and 16(b) are a front elevation and a side elevation,respectively, of the working unit shown in FIG. 15 in a gripping state;

FIGS. 17(a) and 17(b) are a front elevation and a side elevation,respectively, of the working unit of assistance in explaining a powertransmitting method;

FIG. 18 is a side elevation of the working unit of assistance inexplaining a power transmitting method;

FIG. 19 is a schematic perspective view of a medical manipulator in asecond embodiment according to the present invention;

FIG. 20 is a skeleton drawing of assistance in explaining a method ofcontrolling the medical manipulator in the second embodiment;

FIG. 21 is a skeleton drawing of assistance in explaining a method ofcontrolling the medical manipulator in the second embodiment;

FIG. 22 is a table of assistance in explaining a method of controllingthe medical manipulator in the second embodiment;

FIG. 23 is a side elevation of the medical manipulator shown in FIG. 19;

FIG. 24 is a sectional view of a supporting and connecting part shown inFIG. 23;

FIG. 25 is a pictorial view of assistance in explaining a conventionalmedical manipulator, i.e., forcepts;

FIG. 26 is a schematic perspective view of a known medical manipulator;

FIGS. 27(a), 27(b) and 27(c) are diagrammatic views of assistance inexplaining a suturing operation;

FIG. 28 is a perspective view of assistance in explaining the relationbetween the direction of operator's fingers holding an end effectorcontrol unit and the direction of the axis of a fourth joint; and

FIG. 29 is a schematic perspective view of a manipulator having a firstor a third joint serving as a yawing shaft.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic perspective view of a medical manipulator 1 in afirst embodiment according to the present invention, and FIGS. 2 and 3are skeleton drawings of the medical manipulator 1 shown in FIG. 1 ofassistance in explaining the degree of freedom of motion and operationsof the medical manipulator 1.

Referring to FIGS. 1 and 2, the medical manipulator 1 has a working unit10, an operation command unit 20, and a connecting unit 30 havingopposite ends connected to the working unit 10 and the operation commandunit 20.

The working unit 10 has a support unit and an end effector. The supportunit includes a first joint 11 having a first rotation axisperpendicular to the center axis 31 of the connecting unit 30 and asecond joint 12 having a second rotation axis perpendicular to the firstrotation axis of the first joint 11. A gripper 14 included in the endeffector and capable of performing gripping/releasing actions 13 has acenter axis substantially parallel to the second rotation axis of thesecond joint 12. The working unit 10 has a pitching-axis joint 15 and arolling-axis joint 16 supporting the gripper 14 for motions in twodegrees of freedom of motion.

The operation command unit 20 has attitude adjusting unit 23 including athird joint 21 having a third rotation axis perpendicular to the centeraxis 31 of the connecting unit 30 and a fourth joint 22 having a fourthrotation axis perpendicular to the third rotation axis of the thirdjoint 21, and an end effector control unit 24. The end effector controlunit 24 is formed such that directions 201 a and 202 a (FIG. 28) inwhich the fingers of an operator grasping the end effector control unit24 extend are substantially parallel to the fourth axis 22 a of thefourth joint 22. The gripping/releasing action 13 of the gripper 14 iscaused by a control action indicated by the arrow 25 thereinafterreferred to as “control action 25”) of the end effector control unit 24,which will be described in detail later with reference to FIGS. 7 to 10and 28.

In FIGS. 1 and 2, the center axis 31 of the connecting unit 30, thefirst axis of the first joint 11 and the second axis of the second joint12 intersect each other at a single point, and the center axis 31 of theconnecting unit 30, the third axis of the third joint 21 and the fourthaxis of the fourth joint 22 intersect each other at a single point.Although those axes do not necessarily intersect each other at a singlepoint, the gripper 14 revolves along a circular path of an excessivelygreat radius if the offset of the gripper 14 is excessively great. Ifthe offset of the attitude adjusting unit 23 is great, a torque thatcause attitude adjustment acts on the attitude adjusting unit 23 whenposition adjustment is necessary.

Angle sensors, such as encoders or potentiometers, are incorporated intothe operation command unit 20 to measure angles of turning of the thirdjoint 21 and the fourth joint 22. An action sensor, such as an anglesensor or a switch, is incorporated into the end effector control unit24 to measure control actions performed by the operator to operate theend effector 14. The sensors sends signals representing commands 41provided by the attitude control unit 20 to a controller 40. Thecontroller 40 executes predetermined calculations on the basis of theinput commands 41 to drive and control the first joint 11, the secondjoint 12 and the gripper 14.

The gripper 14 can be directly operated for position adjustment becausethe connecting unit 30 connects the working unit 10 and the operationcommand unit 20. The connecting unit 30 as a rolling shaft, the firstjoint 11 as a pitching shaft and the second joint 12 as a rolling shaftenable the gripper 14 to move for motions in three degrees of freedom ofmotion and hence the gripper 14 can be set in an optional attitude. Theconnecting unit 30 as a rolling shaft, the third joint 21 as a pitchingshaft and the fourth joint 22 as a rolling shaft enable the end effectorcontrol unit 24 to move for motions in three degrees of freedom ofmotion and hence the end effector control unit 24 can be set in anoptional attitude. The use of the connecting unit 30 as a common rollingshaft reduces the cost of the medical manipulator 1. An ordinarymanipulator has a problem relating to calculation and a problem that aspecific shaft moves extraordinarily rapidly when the gripper 14 is setin a singular attitude. Since the working unit 10 and the end effectorcontrol unit 20 of the medical manipulator 1 of the present inventionhave the same construction, the medical manipulator 1 of the presentinvention is free from such problems.

A driving unit 10 m including, for example, motors and reduction gearsfor driving the first joint 11 and the second joint 12 for turning anddriving the gripper 14 for the gripping/releasing actions 13 is disposedat a position on the connecting unit 30 near the operation command unit20. The first joint 11 and the second joint 12 of the working unit 10are turned and the gripper 14 of the working unit 10 is driven for thegripping/releasing actins by the driving power of driving devices 11 m,12 m and 13 m included in the driving unit 10 m.

An articulated mechanism including the first joint 11 and the secondjoint 12 of support unit of the working unit 10 and an articulatedmechanism including the third joint 21 and the fourth joint 22 of theattitude adjusting unit 23 are identical. Therefore, the first joint 11turns through an angle by which the third joint 21 is turned, and thesecond joint 12 turns through an angle by which the fourth joint 22 isturned. For example, when the operator turns the third joint 21 forattitude adjustment as shown in FIG. 3, the first joint 11 of theworking unit 10 turns accordingly.

Since the degrees of freedom of motion of the working unit 10 and theoperation command unit 20 of the medical manipulator are designed suchthat the gripper 14 moves in the same direction as that in which theoperator moves the operation command unit 20 for manipulating, forexample, a curved needle for suture as shown in FIG. 27. For example,when the medical manipulator 1 is used for suture, the operator operatesthe operation command unit 20 to move the end effector 14 griping acurved suture needle so that the curved needle is stuck into a part tobe sutured and the curved suture needle moves along a circular path. Thecircular movement of the curved needle coincides substantially with theturning motion of the fourth joint 22, and the third joint 21 and theconnecting unit 30 do not need to be turned through large angles. Thus,the curved needle can be easily manipulated. The conventionalmanipulator carries out the same operations for manipulating the curvedneedle by combined motions of the motions in two degrees of freedom ofmotion of the end effector and the turning motion of the connectingunit. Thus, it is very difficult to manipulate the curved needle by theconventional manipulator for movement along the circular path intendedby the operator.

Any support structure is unnecessary if the medical manipulator 1 isvery lightweight. If the medical manipulator 1 is so heavy that theoperator has difficulty in supporting the medical manipulator 1 for along time or if the medical manipulator 1 needs a holding brakemechanism and a weight compensating mechanism for compensating its ownweight, the medical manipulator 1 may be supported on a supportmechanism 100 as indicated by broken lines in FIG. 1. The medicalmanipulator 1 is supported for turning motions about two axes on avirtual rotation center 110 (fixed point) and for uniaxial linearmotions (motions in a polar coordinate system). For example, the supportmechanism 100 includes a base, a position adjusting mechanism 101capable of vertically moving relative to the base, a rotary unit 102supported on a lower part of the position adjusting mechanism 101 so asto be turnable in a horizontal plane about a vertical axis, and acircular arm 103 having one end connected to the outer circumference ofthe rotary unit 102. The turning axis of the rotary unit 102 intersectsthe virtual rotation center 110 on the center axis 31 of the connectingunit 30. A connecting member 104 connects the other end of the circulararm 103 to the connecting unit 30. The connecting member 104 is able tomove along a circular path on the circular arm 103. The connecting unit30 is extended through the connecting member 104 so as to be linearlymovable along the center axis 31.

FIGS. 4 to 6 show grippers 14 that can be applied to the end effector ofthe working unit 10 of the medical manipulator 1 in the firstembodiment. FIG. 4 shows a gripper 14 having griping members capable ofbeing moved like scissors blades for gripping/releasing actions 13, FIG.5 shows a gripper 14 having gripping members capable of being movedtoward and away from each other for gripping/releasing and FIG. 6 showsa gripper 14 dislocated with respect to the axis of the second joint 12.The gripper 14 may be set in any suitable disposition other than thoseshown in FIGS. 4 to 6, provided that the center axis thereof issubstantially parallel to the axis of the second joint 12.

FIGS. 7 to 10 show the mechanisms of operation command units 20,particularly, end effector control units 24 which may be employed in themedical manipulator 1 in the first embodiment.

The end effector control unit 24 shown in FIG. 7 provides commands foroperating the gripper 14 for gripping/releasing actions when afinger-operated control unit 26 is operated for gripping/releasingactions 25. The finger-operated control unit 26 is provided with twofinger holders 26 a and 26 b for receiving the operator's thumb, and theoperator's index and middle fingers, respectively. At least either thefinger holder 26 a or the finger holder 26 b is supported pivotally on asupport member 27 so that the distance between the finger holders 26 aand 26 b can be optionally changed. When the distance between the fingerholders 26 a and 26 b is changed, the distance between the gripping barsof the gripper 14 changes accordingly. The angle between the fingerholders 26 a and 26 b may be measured and the angle between the grippingbars of the gripper 14 may be adjusted according to the angle betweenthe finger holders 26 a and 26 b. The gripping and the releasingpositions of the finger holders 26 a and 26 b may be detected and thegripping bars of the gripper 14 may be set at gripping positions orreleasing positions.

The end effector control unit 24 shown in FIG. 8 is provided with asupport member 27 having a handle part 27 b. The operator grips thehandle part 27 b with the middle or the little finger to operate the endeffector control unit stably. The end effector control unit 24 may beprovided with the finger-operated control unit 26, a resilient meanscapable of exerting a resilient releasing force or a locking mechanismfor locking the end effector control unit 24 in a gripping state.

The end effector control unit 24 shown in FIG. 9 is provided with ahandle 29 and a switch 28 disposed near the handle 29. The operatorgrips the handle 29 and operates the switch 28 to provide commands todrive the gripper 14 for the gripping/releasing actions 13. If thegripper 14 needs to be driven only for gripping and releasing, thesimple end effector control unit 24 shown in FIG. 9 can be employed Theend effector control unit 24 shown in FIG. 10 is provided with parallelfinger holders 26 a and 26 b capable of being moved toward and away fromeach other.

FIG. 28 is a perspective view of assistance in explaining the operationof the end effector control unit 24 shown in FIG. 1 by the operator'shand 200. The operator's thumb 201 is inserted in a finger holder 26 a,and the operator's forefinger 202 and/or middle finger 203 are insertedin a finger holder 26 b. When the thumb 201, the forefinger 202 and/orthe middle finger 203 are thus inserted in the finger holders 26 a and26 b of the end effector control unit 24, the longitudinal axis 201 a ofthe thumb 201, the longitudinal axis 202 a of the forefinger 202 and thelongitudinal axis 203 a of the middle finger 203 are substantiallyparallel to the axis 22 a of the fourth joint 22 as shown in FIG. 28.The same is true of the end effector control units 24 shown in FIGS. 7to 10.

FIGS. 11 to 16 show working units 10 that may be employed in the medicalmanipulator 1 in the first embodiment. Grippers 14 are in a releasingstate in FIGS. 11, 13 and 15, and grippers are in a gripping state inFIGS. 12, 14 and 16.

The working unit 10 shown in FIGS. 11 and 12 will be described. Arotating member 50 is supported for rotation relative to the connectingunit 30 on the first joint 11. A pulley lip is mounted on the rotatingmember 50. The driving force of the driving device 11 m (FIG. 1) istransmitted to the pulley 11 p by a wire 11 w to rotate the pulley 11 ptogether with the first joint 11 alleys 12 p and 13 p are supported onthe rotating member 50 for rotation relative to the rotating member 50.Bevel gears (or face gears) 51 a and 52 a are fixedly combined with thepulleys 12 p and 13 p, respectively. The bevel gears 51 a and 52 a areengaged with bevel gears 51 b and 52 b, respectively. The driving forcesof the driving devices 12 m and 13 m (FIG. 1) are transmitted to thepulleys 12 p and 13 p by wires 12 w and 13 w, respectively.Consequently, the bevel gears 51 b and 52 b are rotated. The bevel gears51 b and 52 b are supported on the second joint 12 for rotation about anaxis perpendicular to the axis of the first joint 11 supporting therotating member 50. Two shafts 12 a and 12 b are mounted on the shaft12. Gripping bars 14 a and 14 b are fixedly connected to the bevel gears51 b and 52 b by connecting members 53 and 54, respectively, so that thecenter axes thereof are substantially parallel to the axis of the secondjoint 12. Thus the gripping bars 14 a and 14 b can be individuallydriven by the driving devices 12 m and 13 m, respectively. When theshafts 12 a and 12 b are rotated in the same direction, the gripper 14can be turned for rolling. When the shafts 12 a and 12 b are rotated inopposite directions, respectively, the gripper 14 can be driven forgripping/releasing operations. The driving actins of the driving devices12 m and 13 m can be easily determined taking into consideration powertransmitting methods by which the driving forces of the driving device12 m and 13 m are transmitted.

The working unit 10 shown in FIGS. 13 and 14 will be described. Middleparts of a pair of gripping bars 14 a and 14 b are pivotally joinedtogether by a pivot 57. Lower end parts of the gripping bars 14 a and 14b are connected to shafts 12 a and 12 b so as to be turnable about axes55 a and 55 b parallel to the axes of the shafts 12 a and 12 b and aboutaxes 56 a and 56 b perpendicular to the axes 55 a and 55 b,respectively. Driving devices 12 m and 13 m, respectively, drives thegripping bars. The shafts 12 a and 12 b are turned in the same directionto turn the second joint 12 for the rolling motion of a gripper 14. Theshafts 12 a and 12 b are turned in opposite directions, respectively, todrive the gripper 14 for gripping/releasing actions. The movement of thelower ends of the gripping bars 14 a and 14 b can be multiplied byincreasing the length of front parts of the gripping bars 14 a and 14 bextending forward beyond the middle parts pivotally joined together bythe pivot 57.

The working unit 10 shown in FIGS. 15 and 16 will be described. Turningdirections of front parts of gripping bars 14 a and 14 b of a gripper14, extending forward from middle parts of the same pivotally joinedtogether of the working unit 10 shown in FIGS. 15 and 16 relative tothose of back parts of the gripping bars 14 a and 14 b extendingbackward from the middle parts of the same are opposite to those of thefront parts of the gripping bars 14 a and 14 b of the working unit 10shown in FIGS. 13 and 14. The gripper 14 opens when connecting members53 and 54 approaches each other, and closes when the connecting members53 and 54 move away from each other. Since the gripping bars 14 a and 14b are linked to form a toggle mechanism, the gripper 14 is able to exerta very large gripping force when the difference in angular positionbetween the connecting members 53 and 54 is around 180°. Such a verylarge gripping force is available because a direction in which thegripper 14 is opened is nearly perpendicular to a direction in which thelower ends of the gripping bars 14 a and 14 b are moved, and a force toopen the gripper 14 is born by a structure instead of by a drivingdirection. This working unit 10 is suitable for firmly gripping a finesuture needle.

The working units 10 shown in FIGS. 11 to 16 uses the wires, the pulleysand the bevel gears (or face gears) to rotate the shafts 12 a and 12 bon the shaft 12. FIGS. 17 and 18 show other methods.

A method illustrated in FIG. 17 uses only wires and pulleys. The firstjoint 11, and the shafts 12 a and 12 b are driven through wires 11 w, 12w and 13 w, respectively. Pulleys 58 and 59 guide the wires 12 w and 13w along curved paths, respectively. The number of turns of the wire onthe pulley is dependent on angle for driving. A method illustrated inFIG. 18 uses torque tubes 11 t, 12 t and 13 t. The first joint and theshafts 12 a and 12 b are driven by the torque tubes 11 t, 12 t and 13 t,respectively.

The shapes of the structural members, the shafts and the connectingmembers shown in FIGS. 11 to 18 and methods of supporting thosecomponents are not limited to those shown in FIGS. 11 to 18 and may beany shapes or any methods provided that the shapes and the methods donot affect adversely to the function of the medical manipulator. Forexample, the shafts may be fixed and frame may be turned, or the shaftsmay be turned and the frame may be fixed.

FIG. 19 is a schematic perspective view of a medical manipulator in asecond embodiment according to the present invention and FIG. 20 is askeleton drawing of assistance in explaining the operation of themedical manipulator in the second embodiment.

In the medical manipulator 1 in the first embodiment, it is difficult tochange the attitude of the gripper 14 in a direction parallel to an axisperpendicular to the axes of the third joint 21 and the fourth joint 22when the attitude adjusting unit 23 is in a state for setting thegripper 14 in an attitude nearly equal to a singular attitude wherecenter axis 31 of the connecting unit 30 is aligned with or parallel tothe axis of the fourth joint 22 like a state shown in FIG. 19. Themedical manipulator in the second embodiment is designed to improve theoperability of the same when the gripper is set in an attitude nearlyequal to a singular attitude.

The basic configuration of the medical manipulator in the secondembodiment is the same as that of the medical manipulator in the firstembodiment. In the second embodiment, an operation command unit 20 isprovided with a sensor 60, such as a strain gage, capable of sensing aforce acting in a direction perpendicular to the axes of a third joint21 and a fourth joint 22. The sensor 60 is attached to a part of theinner surface of a frame as shown in FIG. 19 to measure bending stressacting in a direction perpendicular to the axes of the third joint 21and the fourth joint 22.

A driving device (actuator) 61 is mounted on a connecting member 104.The driving device 61 is able to drive a connecting unit 30 through abelt-and-pulley transmission mechanism including a belt 63 and pulleys62 and 64. A gear transmission mechanism may be used without anyrestriction instead of the belt-and-pulley transmission mechanism. Acontroller 40 controls the driving device 61 on the basis of measureddata provided by the sensor 60.

When the medical manipulator is in a state shown in FIG. 20 and anoperator operates the end effector control unit to turn the axis of thethird joint 21 in a positive direction 120, the driving device 61 iscontrolled so as to apply a positive torque to the connecting unit 30 tourge the connecting unit 30 to turn in a positive direction 121. If theend effector control unit is operated to turn the axis of the thirdjoint 21 in a negative direction opposite the positive direction 120,the sensor 60 detects a negative bending stress. In this state, thedriving device 61 is controlled to apply a negative torque to theconnecting unit 30 to urge the connecting unit 30 to turn in a negativedirection opposite the positive direction 121.

When the medical manipulator is in a state shown in FIG. 21 with theaxis of the third joint 21 extended in a negative direction and anoperator operates the end effector control unit to turn the axis of thethird joint 21 in a positive direction 122, the sensor 60 detects apositive bending stress and the driving device 61 is controlled so as toapply a negative torque to the connecting unit 30 to urge the connectingunit 30 to turn in a negative direction 123. If the end effector controlunit is operated to turn the axis of the third joint 21 in a negativedirection opposite the positive direction 122, the sensor 60 detects anegative bending stress. In this state, the driving device 61 iscontrolled to apply a positive torque to the connecting unit 30 to urgethe connecting unit 30 to turn in a positive direction opposite thenegative direction 123.

As shown in FIG. 22, a direction in which the driving device 61 turnsthe connecting unit 30 is determined on the basis of the direction ofthe bending stress and the direction of the axis of the third joint 21of the attitude adjusting unit 23. If the third joint 21 is in a neutralattitude singular attitude), the connecting unit 30 may be turned ineither of the opposite directions. In such a case, the connecting unit30 is tuned in a predetermined direction or may be turned in a directionin which the connecting unit 30 has been recently turned to turn theconnecting unit 30 continuously.

The nearer the attitude of the third joint 21 to the singular attitude,the greater is the bending stress. Since the rotating speed must behigh, the torque may be varied in proportion to the bending stress. Therelation between the bending stress and the torque may be determinedproperly so that the operability of the medical manipulator issatisfactory. When the attitude of the third joint 21 is far differentfrom the singular attitude, the bending stress is small and,consequently, the torque decreases automatically, which is desirable inrespect of safety. The torque may be exerted on the connecting unit 30only when the direction of the axis of the third joint 21 is in apredetermined angular range around a neutral direction, such as in anangular range of ±10° with respect to the neutral direction.

If a torque is applied to the connecting unit 30 when the direction ofthe axis of the third joint 21 is in the angular range of ±10°, theworking unit 20 does not move suddenly because the working unit 10 andthe operation command unit 20 are the same in structural configurationand the degree of freedom of motion, and the attitude of the workingunit 10 is analogous with an attitude of the operation command unit 20set by the operator.

The driving device 61 may be used as an actuator for compensating atorque about the center axis 31 of the connecting unit 30 produced bythe weight of the medical manipulator. The torque about the center axis31 produced by the weight of the medical manipulator can be easilycalculated with reference to the attitudes of the shafts of the medicalmanipulator and the torque can be easily compensated.

FIG. 23 is a view of assistance in explaining a method of applying atorque about the center axis 31 of the connecting unit 30 to theconnecting unit 30. The medical manipulator 1 is supported on theconnecting member 104 so as to be turnable about the center axis 31 ofthe connecting unit 30 and to be linearly movable in parallel to thecenter axis 31 of the connecting unit 30. As shown in FIG. 23, theconnecting unit 30 is supported in a linear-motion bearing 65 and arotary bearing 66. The connecting unit 30 has a D-shaped cross-section.The driving device 61 turns the sleeve 67 of the linear-motion bearing65 through the belt-and-pulley transmission mechanism including the belt63 and the pulleys 62 and 64. Thus, the connecting unit 30 is supportedon the connecting member 104 for linear movement and rotation, andtorque can be applied to the connecting unit 30.

In the first and the second embodiment, the first joint 11 or the thirdjoint 21 is a pitching shaft. However, the first joint 11 or the thirdjoint 21 does not need necessarily to be a pitching shaft and may be ayawing shaft as shown in FIG. 29.

As apparent from the foregoing description, according to the presentinvention, since the support unit is able to change the attitude of theend effector in two or more degrees of freedom of motion, the operationcommand unit and the working unit are connected mechanically by theconnecting unit, and the operator's actions, such as actions formanipulating a curved suture needle for suturing, and the actions of themanipulator are identical, the operation command unit can be smoothlymoved in a direction desired by the operator. Thus, the manipulator isexcellent in operability. Since operating force exerted by the operatoris assisted by power when the end effector is set in a singular attitudeor an attitude similar to the particular attitude, the operability ofthe end effector in particular directions does not becomes quiteunsatisfactory and the end effector is able to exert a sufficiently highgripping force.

Although the invention has been described in its preferred embodimentswith a certain degree of particularity, obviously many changes andvariations may be made therein. It is therefore to be understood thatthe present invention may be practiced otherwise than as specificallydescribed herein without departing from the scope and spirit thereof.

FIG. 22

1 . . . Third joint, 2 . . . Bending stress, 3 . . . Torque

FIG. 26

1 . . . Yawing axis, 2 . . . Pitching axis, 3 . . . Pitching axis, 4 . .. Yawing axis

1-8. (canceled)
 9. A method for suturing with a manipulator: griping a curved suture needle; sticking the curved suture needle into a part to be sutured; and turning a support unit, wherein the manipulator includes, an operation command unit including an attitude adjusting unit and an end effector control unit, a connecting unit having one end connected to the operation command unit, and a working unit connected to the other end of the connecting unit and provided with an end effector and the support unit supporting the end effector for motion.
 10. The method for suturing according to claim 9, wherein the support unit supports the end effector for motions in at least two degrees of freedom of motion.
 11. The method for suturing according to claim 9, wherein the support unit includes a first joint configured to turn about a first axis perpendicular to a center axis of the connecting unit, and a second joint configured to turn about a second axis perpendicular to the first axis, and the end effector includes a center axis substantially parallel to the second axis.
 12. The method for suturing according to claim 11, wherein the turning the support unit includes turning the second joint.
 13. The method for suturing according to claim 12, wherein the attitude adjusting unit includes a sensor for transmitting an operation command to turn the second joint.
 14. The method for suturing according to claim 9, wherein the manipulator includes a control unit configured to transmit an operation command provided by the attitude adjusting unit to the support unit to adjust the attitude of the end effector and configured to transmit an operation command provided by the end effector control unit to the end effector to operate the end effector.
 15. A method for suturing with a manipulator: griping a curved suture needle; sticking the curved suture needle into a part to be sutured; and turning a support unit, wherein the manipulator includes, an operation command unit provided with an attitude adjusting unit and an end effector control unit; a connecting unit having one end connected to the operation command unit; a working unit connected to the other end of the connecting unit and provided with an end effector and the support unit supporting the end effector for motions in at least two degrees of freedom of motion; and a control unit that transmits an operation command provided by the attitude adjusting unit to the support unit to adjust the attitude of the end effector and transmits an operation command provided by the end effector control unit to the end effector to operate the end effector; wherein the support unit includes a first joint capable of turning about a first axis perpendicular to a center axis of the connecting unit, and a second joint capable of turning about a second axis perpendicular to the first axis; and the end effector control unit has a handle part to be gripped by fingers and a longitudinal direction is substantially in parallel to the first axis. 